Self-assembly of a barnacle cement protein into intertwined amyloid fibres and determination of their adhesive and viscoelastic properties

Abstract

The stalked barnacle Pollicipes pollicipes uses a multi-protein cement to adhere to highly varied substrates in marine environments. We investigated the morphology and adhesiveness of a component 19 kDa protein in barnacle cement gland- and seawater-like conditions, using transmission electron microscopy and state-of-the art scanning probe techniques. The protein formed amyloid fibres after 5 days in gland-like but not seawater conditions. After 7–11 days, the fibres self-assembled under gland-like conditions into large intertwined fibrils of up to 10 µm in length and 200 nm in height, with a distinctive twisting of fibrils evident after 11 days. Atomic force microscopy (AFM)-nanodynamic mechanical analysis of the protein in wet conditions determined E ′ (elasticity), E ′′ (viscosity) and tan δ values of 2.8 MPa, 1.2 MPa and 0.37, respectively, indicating that the protein is a soft and viscoelastic material, while the adhesiveness of the unassembled protein and assembled fibres, measured using peak force quantitative nanomechanical mapping, was comparable to that of the commercial adhesive Cell-Tak™. The study provides a comprehensive insight into the nanomechanical and viscoelastic properties of the barnacle cement protein and its self-assembled fibres under native-like conditions and may have application in the design of amyloid fibril-based biomaterials or bioadhesives.

Adaptive Adhesions of Barnacle-Inspired Adhesive Peptides

“…This is an interesting result, which could not be easily deciphered from the force profiles in SFA measurements and the acoustic sensing by QCM. Nevertheless, it is consistent with the previously proposed self-assembly mechanism of barnacle cement protein, with secondary structures likely similar to our peptides, where the seawater condition including both a basic pH and high salt concentration could serve as a trigger to stimulate the fiber formation of barnacle cement proteins. − ,, …”

“…Nevertheless, it is consistent with the previously proposed self-assembly mechanism of barnacle cement protein, with secondary structures likely similar to our peptides, where the seawater condition including both a basic pH and high salt concentration could serve as a trigger to stimulate the fiber formation of barnacle cement proteins. [23][24][25]38,39 Rationalizing the Peptide Sequence Design for Adaptive Adhesions. From the SFA adhesion measurement, Mr-AP1C was shown to establish stronger adhesion than Mr-AP1 in all environment conditions used in this study (Figure 3).…”

Mapping the Nanoscale Heterogeneous Responses in the Dynamic Acceleration of Deformed Polymer Glasses

“…In this study, we report the direct mapping of the evolution of relaxation dynamics at the nanoscale in a glassy polymer with increasing compressive stress. We employ a new experimental approach based on AFM in nanorheology mode, also known as nanoscale dynamic mechanical analysis (nDMA), which has been recently proved capable of quantifying linear mechanical dynamics of polymers at the nanoscale. − The measurements were performed on a solvent casting poly­( n -butyl methacrylate) (PnBMA) film using probes with a radius of ∼8 nm. Details about the sample preparation and experimental methods are provided in the Supporting Information.…”